• H Hartley Sweeten's avatar
    ARM: ep93xx: switch to SPARSEMEM · 80320927
    H Hartley Sweeten authored
    
    
    The EP93xx has four chip selects that can be used for the SDRAM memory.
    These chip selects are decoded to specify an address domain:
    
      SDCS3  0x00000000-0x0fffffff with Boot Option ASDO=1
      SDCS0  0xc0000000-0xcfffffff
      SDCS1  0xd0000000-0xdfffffff
      SDCS2  0xe0000000-x0efffffff
      SDCS3  0xf0000000-0xffffffff with Boot Option ASDO=0
    
    Because of the row/column/bank architecture of SDRAM, the mapping of
    these memories into the processor's memory space is discontiguous.
    
    Most ep93xx systems only use one of the chip selects. For these systems,
    ARCH_HAS_HOLES_MEMORYMODEL has worked fine to handle the discontiguous
    memory.
    
    But, some of the TS-72xx boards use multiple chip selects. The TS-7300 in
    particular uses SDCS3 (with ASDO=1) and SDCS2. On that system with
    ARCH_HAS_HOLES_MEMORYMODEL the SDCS2 memory does not get handled correctly
    and results in the system not booting.
    
    Change the EP93xx to ARCH_SPARSEMEM_ENABLE. This handles the discontiguous
    memory for all configurations.
    
    This has been tested on the following ep93xx platforms:
    
    EDB9307A with 64 MiB on SDCS0
    Vision EP9307 with 64 MiB on SDCS0
    TS-7300 with 64 MiB on SDCS3 (with ASDO=1) and 64 MiB on SDCS2
    sim.one with 64 MiB on SDCS0
    
    Signed-off-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
    Tested-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Cc: Russell King <linux@armlinux.org.uk>
    Tested-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
    Tested-by: default avatarAlexander Sverdlin <alexander.sverdlin@gmail.com>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    80320927